In recent years, with the expansion of computer networks, there has been an increasing demand for an increase in storage capacity for disk storage apparatuses typified by hard disk drives (HDDs). In particular, in the field of the Internet, for example, attention has been paid to a storage environment called “cold storage”. The cold storage environment is an environment in which there is a high probability that data stored in the HDD is left as such, without being accessed. In such a storage environment, it is required to construct such an environment that a large capacity of data is stored with use of a HDD in which more importance is placed on storage capacity than on access performance.
For the construction of the storage environment in which importance is placed on storage capacity, it is necessary to increase the whole storage capacity on the disk in preference to access performance. In conventional HDDs, a storage area on the disk, at which a quality relating to access performance has degraded, is rendered non-usable, and a storage area, at which a high quality can be obtained, is used.